THE CENTRAL PROBLEM OF PURGEGATE. As the story expands, it's worth returning to this post by Josh Marshall, which in addressing the inevitable tu quoque rejoinders lays out the central problem with this particular series of firings. Presidents are, of course, entitled to set law enforcement priorities, and Bush may fire U.S. Attorneys for reasons that I would consider substantively wrong but not illegitimate, such as failing to enforce immigration laws effectively enough or refusing to seek the death penalty in all circumstances. (If you disagree, would you also believe that it's illegitimate for a Democratic President to fire a U.S. Attorney who insisted on taking resources away from investigating corporate fraud or violent crimes in order to prosecute marijuana possession cases?)
In this case, however, the attorneys were fired for reasons of strict partisanship, for "not sufficiently politicizing their offices, for not indicting enough Democrats on bogus charges or for too aggressively going after Republicans." That's an entirely different issue; using the law to arbitrarily harass political opponents (or exempt political allies from punishment) is a wholly illegitimate subversion of the legal system, as is firing U.S Attorneys because they refuse to do so. Relatedly, this is also what makes Bush v. Gore such a uniquely awful decision; highly contestable rulings that are broadly consistent with one's policy preferences are one thing (it's inevitable, and done by both sides), but favoring a particular litigant and partisan electoral outcome while both contradicting one's previously expressed legal principles and trying not to create a binding precedent that might not work to similar partisan advantage in the future is particularly appalling. It really was the appropriate way to make Bush's ascension to the presidency official.